I spray the tank down to increase the humidity. The setting of high is the humidity up to or greater than 90%. Using screened aquariums, I have to spray them both down three times daily. I also keep dry towels on top of the tanks. When shed times comes, once a month, I don't spray more I just wet the towels down. Then humidity stays high. This is also the time when I change the aspen bedding. That way I avoid bacteria growth, and belly rot.